• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 춘계학술대회논문집; 전남대학교, 19 May 1995
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• pp.307-312
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• 1995

장거리 시스템의 경우에 있어서 기동과 정지 시의 동적하중은 구동부 입력크기의 변화와 구동부간이 기동 시간차이로부터 발생되며, 벨트로 전파되어 장력변화를 일으키고, 과도한 장력의 변화는 인장과 압축의 탄성파로 벨트요소의 응력을 증가시키며, 벨트, 풀리, 아이들러(idler)등의 벨트요소들을 파괴시킨다. 따라서 동적해석에 의한 설계가 필수적으로 요구되어 벨트의 동적거동 해석에 대한 연구가 많이 수행되고 있다. 본 연구에서는 벨트 컨베이어 시스템을 집중질량모델(lumped mass model)로 근사하여 모델링하는 방법을 도입하여 세부요소에 대한 운동방정식을 유도하고, 각 요소 모델링을 결합하여 전체 운동방정식을 수립하였으며, 예제 시스템에 적용하여 동적거동을 해석하였다. 예제 시스템에 있어서 기동시의 구동입력을 두 가지 형태의 입력을 이용하였고, 정지시에는 구동부 브레이크가 없는 경우로 정상운전상태에서 순간적으로 구동부의 동력을 제거하는 방법을 적용하였다. 시뮬레이션 결과를 통하여 기동시의 구동입력을 적절히 제어하므로 벨트 속도와 장력의 변화를 줄일 수 있는 입력형태를 결정할 수 있었고, 이 때의 테이크업의 운동도 구할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.321-323
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• 1999

유도기의 과도 상태를 해석하기 위해 시간 차분 유한요소법 대신 자기 등가 회로법을 적용하기 위한 연구가 있어왔다. 이 방법은 기기의 각 부분을 자기적 회로로 변환하여 해석하는 것으로 계산 시간이 짧고 정화한 장점이 있다. 이 방법으로 해석하기 위해서는 기기의 각 부분을 자기적 요소로 바꾸어야 하고, 에너지 변환이 일어나는 공극을 퍼미언스로 나타내야 한다. 따라서 이 논문에서는 먼저 자기 등가 회로법으로 해석할 수 있도록 공극 퍼미언스로 구성되는 매트릭스를 제시하여, 차후 시스템 매트릭스를 구성할 때 사용코자 한다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.771-774
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• 2009

불규칙입력에너지 발전시스템에 이차여자 권선형 유도기를 적용하고 그의 해석에 대하여 다루었다. 불규칙적으로 변화하는 입력에너지에서 안정된 출력에너지를 얻기 위하여 시스템의 과도적 상태를 해석할 필요가 있다. 이에 본 연구에서는 교류기해석에 사용되는 2축 이론으로 1, 2차 측 전류, 전압, 출력 등 변수의 값을 해석할 수 있게 하였다. 최종적으로 전압전원형 인버터를 마이크로프로세서를 이용하여 안정된 출력을 얻는데 성공하였다.

• 한국유체기계학회 논문집
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• 제3권2호
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• pp.24-30
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• 2000

The structural analysis of a reactor coolant pump(RCP) of a nuclear power plant is very important for the safety assessment of the plant. Accurate boundary conditions for the heat transfer coefficient are required for reliable thermal stress analysis of the pump casing, especially in transient operations of the pump since the coolant properties are largely dependent on operational conditions. In the present study, a 3D mixed flow type coolant pump was modeled from the RCP drawings and analyzed in the steady state and number of transient flow conditions by using a commercial code STAR-CD. From the result of the computation, it is seen that the average heat transfer coefficients for the cases considered are found to be the suggested values of the manufacturer, Westinghouse Energy System. The unevenness in local heat transfer coefficients, however, is found to be considerable so that the use of average heat transfer coefficients in all boundaries might not give reliable thermal stress predictions.

• 한국소음진동공학회논문집
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• 제14권5호
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• pp.424-431
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• 2004

An implicit direct-time integration method for obtaining transient responses of general dynamic systems is described. The conventional Newmark method cannot be directly applied to state-space first-order differential equations, which contain no explicit acceleration terms. The method proposed here is the state-space Newmark method that incorporates the average velocity concept, and can be applied to an analysis of general dynamic systems that are expressed by state-space first-order differential equations. It is also readily coded into a program. Stability and accuracy analyses indicate that the method is numerically unconditionally stable like the conventional Newmark method, and has a period error of 2nd-order accuracy for small damping and 4th-order for large damping and an amplitude error of 2nd-order, regardless of damping. In addition, its utility and validity are confirmed by two application examples. The results suggest that the proposed state-space Newmark method based on average velocity be generally applied to the analysis of transient responses of general dynamic systems with a high degree of reliability with respect to stability and accuracy.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.465-470
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• 2003

In this study, the state-space Newmark method based on average velocity is presented to analyse the transient dynamic response for general dynamic system. The conventional Newmark method based on average acceleration cannot he directly to the first-order state-space differential equations introducing the state-space vector. To overcome this problem, the time-step integration algorithm, based on average velocity concept, suitable for the first-order state-space differential equations is proposed In results, the proposed method has %he numerical stability and order of accuracy, which is proved analytically, equal to those of the conventional Newmark method based on average acceleration. Also, the formulation for numerical solution is very simple and the calculation time Is nearly equal to that of the conventional Newmark method based on average acceleration in spite of an increase of two times over matrix size. This method will be look forward to applying the general dynamic system to calculate the transient dynamic response.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.669-674
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• 2004

In this study, the analytical method to evaluate the response of rotor-bearing system subjected to base excitation was presented. The equations of motion contain speed dependent gyroscopic terms, base rotation dependent parametric terms and several forcing function terms which depend on linear accelerations, rotational accelerations and a combination of linear and rotational combination. The study of rotor-bearing system excited by its base motion is not only able to predict the rotational performance, but provides the fundamental data for vibration isolation. In order to illustrate transient response, transient response analysis of a practical application sample were performed. The transient response was carried out for the given base excitation by using the state-space Newmark method that incorporates the average velocity concept.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.18-20
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• 2002

In this paper, the construction elements of the induction motor was represented by the magnetic tube. The magnetic tube is basis of the magnetic equivalent circuit. The magnetic equivalent circuit method is convenient of complicated analysis of the transient state of the induction motor. Because the method is restriction on only one direction of magnetic flux. Air gap magnetomotive force was calculated by magnetic equivalent circuit method. Starting transient torque and phase current of the induction motor was confirmed by the theoretical calculation and the experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.147-149
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• 2001

The single-phase line-start permanent magnet motor has been shown to be capable of very desirable steady state performance, but known to have undesirable starting performance. This is because magnetic braking torque. So, it is very important to predict starting performance accurately when designing the line-start motors. In this paper, starting performance was calculated by combination of d-q axis voltage equations and mechanical dynamic equations. D-q axis voltage components were derived by winding angle and turns ratio transformations.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.439-444
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• 2005

Steady state simulation and dynamic simulation were performed to analyze the operational characteristics of a multi-type refrigeration system, Fully distributed model was adopted to simulate the steady state and transient responses of the system. The main aim was to see the effect of one indoor unit on the other unit. Numerical simulations were carried out for various operation conditions of an indoor unit - secondary fluid inlet temperature, mass flow rate and expansion valve opening. The results showed that the inlet temperature and mass flow rate of the secondary fluid of one indoor unit had minor effect on the operation of the other unit. However, the opening of the expansion valve had significant effect on the performance of the other unit.